Routing and navigation systems sometimes rely upon probe data consisting of a plurality of probe points. In this regard, probe points are representative of travel along a road. The probe points may be collected by a variety of different data collection devices, such as a global positioning system (GPS), navigation systems, location tracking systems or the like. These data collection devices may be carried by vehicles, for example, as the vehicles travel along the roads. For example, the data collection devices may be mounted within the vehicles, such as a component of a navigation system, an advanced driver assistance system (ADAS) or the like, or may be carried by passengers within the vehicle, such as in an instance in which the data collection device is embodied by a mobile terminal, tablet computer or other portable computing device carried by the passenger riding within the vehicle. The data collection devices repeatedly capture probe points as the data collection devices move along a respective road, such as by capturing probe points at a predefined frequency. Each probe point defines a location at which the probe point was captured, such as in terms of latitude and longitude. The probe point may also include or otherwise be associated with a variety of other information including, for example, the speed of the vehicle, the time at which the probe point was captured, the heading of the vehicle, etc.
Based upon an analysis of probe points, a routing or navigation system can identify instances in which a road has changed course and/or in which a new road has been constructed. Further, based upon the probe points, a routing and navigation system may estimate travel time along a route from an origin to a destination. In this regard, a routing and navigation system may determine the time expended for vehicles represented by probe points to travel the same route or at least a portion of the route and, based on this information, estimate the travel time along the route during a corresponding time period.
In instances in which the number of probe points along a respective road is relatively few, however, the use of the probe points by a routing and navigation system may produce results that are less accurate than are desired. For example, with only a few probe points along a road, the travel time that is estimated for a route that includes travel along the road may be less accurate than is desired since the relatively few probe points may not accurately represent the travel time incurred by other vehicles. This challenge relating to the reliance upon probe points by routing and navigation systems in instances in which only a relatively few probe points are identified along a road is particularly notable on roads that are less well traveled including, for example, many roads within a residential neighborhood.
Further, since not all vehicles and, in some instances, only a small percentage of all vehicles on a road provide probe points, the penetration rate, that is, the fraction of vehicles that provide probe points relative to the total number of all vehicles on a road, is generally relatively low. Consequently, routing and navigation systems may find it difficult to estimate traffic flow from the probe data. In this regard, the probe data that is collected may not allow the actual traffic density, that is, the actual number of vehicles on the road over a particular length of the road, to be determined since the vehicles that provide probe points are less than all of the vehicles on the road and the total number of vehicles on the road is correspondingly unknown. Thus, while estimates of traffic flow would be useful for routing and navigation systems and, in turn, the subscribers of routing and navigation systems, traffic flow has not generally been able to be reliably estimated based upon probe data.